Indications and Contraindications of the Maryland Bridge

Indications:
• Periodontal Splinting
• Replacement of missing teeth
• Prosthodontic splinting
• Combination with Removable Partial Denture
• Changes in Occlusal table
• Strengthening Natural Teeth

Contraindications:
• Sensitivity to base metal alloys
• Changes in facial esthetic of abutments (Long spans - Inadequate enamel for bonding)
• Poor quality enamel
• Short clinical crowns
• Narrow embrasures
• Incisors with thin buccal lingual dimensions
• Pathologic occlusion (i.e.- bruxism)
• Malocclusion
• High caries rate or high caries risk

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Denture Reline and Rebase

Introduction:

A reline is a procedure used to re-fit the surface of a denture to the tissues of the mouth.
This is done by placing a new acrylic base into the denture, duplicating the new form of the oral structures in the mouth.
A reline will bring back comfort to the patient, stability to the denture and discourage food from going underneath it.
Relines are required for many reasons with the most common reason being gum resorption (shrinking of the oral tissues).
Gum resorption is caused by the normal process of aging or after natural teeth have been extracted.
A general rule of thumb is that dentures should be relined once every 2 to 3 years.
Relines are a normal part of denture maintenance and important to the health of the oral tissues and bone support of a denture wearer.
A reline is not always recommended for a denture, If a denture has lost some retention and the "bite" or occlusion has changed considerably, a reline will not be satisfactory in correcting the retention of this denture.

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Types of Relines:

A- Temporary Reline:
A temporary reline (tissue conditioner) is a silicone gel designed to last 1 to 4 months.
It is normally used in dentures of people who have had their natural teeth extracted or to improve the health of their tissues before new dentures are made.

B- Direct Reline:
A direct reline is also called a chair side reline.
The direct reline material is inserted in the denture and sets in the mouth as the patient waits in the dental chair.
The direct reline is offered in a hard or soft base, and are not meant as a long term solution to fit issues.

C- Processed Reline:
A processed reline is completed by taking an impression inside of the patient's existing denture duplicating the new form of the oral structures in the mouth.
This impression is then processed in our in-house laboratory for approximately 7 hours.
This is considered a permanent reline due to the high quality of material used and the precision of the fit achieved.

D- Soft Reline:
A soft liner is used mainly in full lower dentures and allows for more protection and comfort for people who have sensitive gums with little or no bone support.
The soft base is a liner that is bonded into your denture.
Your denture will adhere better to what remains of your gum, be less irritating to your tissues and give your denture more stability.
When constructing a denture, the Prosthodontist will take an impression for the soft base and process it into the inside of the denture.
The Soft liner material is a bonded medical grade rubberized base.
Soft liners will last approximately 2 years.
Remember: relines do not change the color or shape of the teeth or make them sharper for chewing, A reline replaces the fitting surface of the denture to make it fit better.

E- Rebase
A rebase is the process of refitting a denture by replacing the entire denture base.
This procedure is done by taking a new impression inside the denture, completely removing the old acrylic and adding a new acrylic base around the existing teeth.
This service is recommended for dentures that have had multiple repairs, discoloration or are very thin.

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Precision Attachment

- Definition:
It's part of a Dental Prosthetic Design that aims to connect a partial denture to fixed bridgework. can be used to restore arches where there are not enough teeth for fixed bridgework.

- Parts:
The Precision Attachment consists of two parts, Female and Male parts, the male part is attached to the partial denture, while the female part is soldered to fixed crowns or bridgework.

- Advantages:
1- Cosmetic Appearance.
2- Maintainable Periodontal Health.
3- Longevity of Abutment Teeth.
4- Patient Comfort.
5- Questionable Teeth can be saved in a way that does not affect case.
6- Longevity if they are lost in the future.
7- Natural Tooth and/or Implant Abutments can Be Used.
8- Can Be Adapted to Compensate for Future Changes in the Mouth.

- Function:
- There is no mechanical locking in the design of the Precision Attachment.
- A good precision attachment partial denture will not dislodge during normal function.
- The path of insertion of the male part inside the female part is different from the pull of the muscles and the action of the tongue and gravity, so that dislodging does not happen.
- It can move in a "vertical direction" slightly to release the forces instead of passing along them to the abutment teeth, The result is "physiologic stimulation" of the abutment teeth and the edentulous ridges.

- Requirements:
- All the teeth that support bridgework are prepared with full shoulder preparations in three-dimensions.
- Any defects must be corrected surgically, to create as healthy environment as possible.
- Minimize occlusal forces by: narrow occlusal (biting surface) diameters, adequate room for hygiene, proper length and anatomy, solid and passive fit, and adequate occlusion (bite) at the correct jaw relationship.
- Must be used in a precise manner in order to maintain a high percentage of longevity.
- Precision attachment cases must fit with precision.
- The abutments must be stable.
- The frameworks must fit properly without rock.
- Steps should be followed accurately without dismissing to avoid complications.

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Denture Support, Retention and Stability

Denture Stability: It's the resistance of the denture against Any-Direction movement.
Denture Retention: It's the resistance of the denture against movement away from the tissues.
Denture Support: It's the resistance of the denture against movement toward the tissue.

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Denture Support:
- Periodontal Ligament around the natural teeth should be 2.5 times more than the complete denture bearing area on the mucosa.

- To achieve the best support for the denture, try to make a maximum area as much as possible.

- The Primary Support Areas are:
A- Mandible: Buccal Shelf of bone and Retromolar Pad.
B- Maxilla: Horizontal Portion of the hard palate.

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Denture Retention:
- The Primary Retention methods are:
A- Border Sealing of the Denture.
B- Neuromascular Control.
C- Physical (Adhesive) forces: Salive-Denture base and Saliva-Mucosa.

- The Criteria of the great retentive force are:
A- The Salive film covers the whole surface area of the denture.
B- The Denture Base extends the full length in the sulcus.
C- Border Seal prevent the ingress of the saliva and air.

- Elements of the great retentive force are:
A- Total Surface area. (More surface area=More retention)
B- Viscosity of the saliva. (More Saliva Viscosity=More retention)
C- Distance between the denture base and the mucosa. (More Distance=Less retention)

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Denture Stability:
- Factors affecting the Denture Stability:
A- Denture Base Adaptation.
B- Ridge Anatomy.
C- NeuroMascular Control.
D- Occlusal Harmony.

- Ridge Anatomy effect the Denture Stability By:
A- Large, Square and Broad Ridges.
B- Steep Palatal Vault.
C- Firm Vs. Flabby Ridges.

- NreuroMascular Control effect the Denture Stability By making the denture borders to be polished to allow the tongue, cheek and lips to seat the denture during function.

- Occlusal Harmony effect the Denture Stability By:
A- Bilateral, simultaneous posterior tooth contacts in retruded jaw relationship.
B- Free of the Occlusal interferences.
C- Acceptable level of the mandibular occlusal plane.
D- Teeth set close to the natural teeth position.

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